Fuel supply apparatus for resonant pulse jet combustion device



Sept. 13, 1955 FUEL SUPPLY APPARATUS FOR RESONANT PULSE JET COMBUSTIONDEVICE L. R. HUBER 2,717,637

Filed June 3, 1952 BY PM I W 1, M, fimwr ATTORNEY United States Patent OFUEL SUPPLY APPARATUS FOR RESONANT PULSE JET COMBUSTION DEVICE Ludwig R.Huber, Uberlingen am Boden See, Germany, assignor, by mesne assignments,to Swingtire (Bahamas) Limited, Nassau, Bahamas, a corporation of theBahamas Application June 3, 1952, Serial No. 291,367

Claims priority, applicationSwitzerland May 30, 1947 10 Claims. (Ci.158-4) This invention relates to apparatus for supplying fuel to aresonant pulse jet combustion device.

This application is a continuation-in-part of my copending applicationSerial No. 28,917, filed May 24, 1948, now abandoned, and entitledProcess and Means for the Measured Admixture of a Fluent Material 'in aCyclic valve or check valves connected to the combustion chamher. Thecombustion chamber pressure periodically fluctuates, at the naturalfrequency of the apparatus, between superatmospheric and subatmosphericvalues, and the fuel and air for combustion are drawn into the chamherwhen this pressure is subatmospheric. The periodic interval when thepressure is subatmospheric may be termed the suction phase of operationand the period when the pressure is superatmospheric may be termed thedetonation phase of the operation. Resonant pulse jet combustionapparatus of this nature is disclosed, for example, in the copendingapplication of Walter Diirr et-al., Serial No. 166,611, filed June 7,1950, and entitled Burner Device Having Heat Exchange and Gas FlowControl Means for Maintaining Pyrophoric Ignition Therein, now PatentNo. 2,644,512. Apparatus of this nature is useful to provide a reactiondrive for airplanes, heating devices, apparatus for atomizing andspraying liquids and for other purposes.

In earlier embodiments of resonance pulse jet cornbustion devices, fuelhas been fed into the combustion .9;

chamber from carburetor or nozzle discharging fuel through the checkvalve that periodically admits air to the combustion chamber. Thisarrangement has the disadvantage that the check valve mechanism iswetted and so damaged by the fuel. For this reason, efforts have beenmade to introduce fuel through a nozzle or the like which opens into thecombustion chamber inside the air admission check valve. In previouslyproposed arrangements of this kind, the fuel is periodically forced backfrom the nozzle mouth by the detonation phase pressure in the combustionchamber to such an extent that the vacuum in'the chamber during theensuing suction phase .is insufficient to draw the fuel back to andthrough the nozzle mouth and into the combustion chamber in time tosupport the next ensuing detonation.

It is the object of the present invention to provide a novel fuel supplyapparatus for combustion devices of the type described which permits thereliable introduction of fuel to the combustion chamber during thesuction phase of operation and without passing the fuel through a .checkvalve. in accordance with the invention, this object is accomplished byconnecting to the combustion operation.

or cyclone action.

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chamber a venturi tube having a restricted throat intermediate its ends,into which throat a fuel feed pipe discharges. Due to the periodicpressure fluctuations in the combustion chamber, gases are forced toflow alternately in opposite directions through the venturi tube, withthe result that fuel is drawn into the tube from its throat both whenthe flow is toward the combustion chamber during a suction phase andwhen the flow is away from the combustion chamber during a detonationphase of Thus, a combustible mixture of air and fuel is drawn into thecombustion chamber during a suction phase of operation and exhaust gasis forced out of the combustion chamber through the venturi tube duringa detonation phase of operation. With this arrangement, a supply of fuelis constantly maintained at the mouth of the fuel pipe where it opensinto the throat of the venturi tube, so that fuel is at all timesavailable for introduction into the combustion chamber without delayduring a suction phase of operation. The fuel drawn into the combustionchamber during the suction phase of operation supports combustiontherein during the ensuing detonation phase. The fuel drawn from thefuel feed pipe (it ing the detonation phase is carried into acondensation chamber connected to the outer end of the venturi tube andis there condensed and preferably returned from that chamber to the fuelfeed pipe or to a fuel supply container to which the feed pipe isconnected. Although not essential to the invention, the condensationchamber may be designed to separate fuel from gasesby centrifugal Thecondensation chamber may, however, comprise a fuel supply container,such as the float chamber from which fuel is fed to the venturi throat,and in this connection, the flow of gases through the narrow venturithroat does not disturb the normal operation of the float.

ln-describing the invention in detail, reference will be made to theaccompanying drawings, in which an embodiment thereof is illustrated.

In the drawings- Fig. l is a sectional elevation of apparatus embodyingthe invention;

Fig. 2 is an enlarged sectional elevation taken along the line 22 ofFig. 1 and viewedin the direction of the arrows, and

Fig. 3 is a horizontal section view taken along the line I 33 of Fig. 2and viewed in the direction of the arrows.

eferring to the drawing, there is shown a combustion chamber 2 havingconnected thereto a valveless exhaust pipe or resonance tube 1 whichtogether form a resonant pulse jet combustion device. Air for supportingcombustion in the chamber 2 is periodically drawn into the chamberduring the suction phase of operation through one or more check valves 3of suitable construction which are connected to the chamber 2 by aninlet passage 4. Fuel is drawn into the combustion chamber during thesuctionphase from a narrow venturi tube 6 opening into the inlet passage4 and the air and fuel mixture is ignited and so detonated by anignition plug 5 or by compression.

According to the invention, the outer end of the venturi tube 6 isconnected to a condensation chamber so that the venturi passage directlyconnects the combustion chamber with the condensation chamber Withoutany intervening check valve. As shown, the condensation chamber 10 maytake the form of a centrifugal separator having a bafile 12 fordirecting the fuel and gas mixture in a spiral path, as illustrated bythe broken arrow. A pipe 13 conducts air and such fuel or fuel vapor asmay be expelled from the condensation chamber 10 during a detonationphase of operation, from the condensation chamber ltl to a point nearthe air intake check valves 3, from which point the air and fuel aredrawn into the air inlet of the combustion device. In some cases thepipe 13 may be omitted. The condensation chamber 10 opens into a fuelsupply container, here shown as a float chamber 7 disposed below thechamber 10. Fuel from a suitable supply enters the chamber 7 through apipe 9 under control of a float operated valve 15.

The venturi tube 6 is formed of two conical passages 14 and 19 meetingat a restricted throat into which a ring channel 18 surrounding thethroat opens. The ring channel 18 is connected to the float chamber 7through a fuel pipe 8 having a metering orifice 11 therein.

During operation of the device, gases flow through the venturi tube 6alternating in opposite directions. When the flow is toward thecombustion chamber, fuel is drawn from the ring channel 18 at the throatof the venturi tube .w

and is drawn into the combustion chamber. When the flow is outwardtoward the condensation chamber 10, fuel is similarly drawn from thering channel 155 and entrained with the gas, and this fuel is condensedin the chamber 19 and returned to the fuel supply container illustratedas the float chamber 7, and so is eventually returned to the ringchannel through the fuel pipe 8. Since fuel is drawn from the ringchannel 18 during both the suction cycle and the detonation cycle of thedevice, fuel is at all times present at the mouth of this channel and isdrawn into the venturi tube and entrained with the entering air withoutdelay at the start of each suction cycle.

The spiral path of the gaseous mixture in the condensation chamber 19due to the baffle 12 assists in separating the fuel from the gases inthis chamber, but this is not essential to the invention in its broaderaspects. In fact, the separation of the fuel from the gases and itsreturn to the fuel feed pipe, while constituting a desirable innovation,is not essential to my broader concept of feeding fuel to the restrictedthroat of the venturi tube so that fuel is dependably drawn into thecombustion chamber during a suction phase of operation, and this withouteither feeding the fuel through the air intake check valve, employing afuel pump, or employing a 4 check valve in the fuel feed pipe.

In order to insure that a sufficiently low pressure is provided at thering channel 18 during the detonation cycle of operation to cause fuelto be drawn from the ring channel during that cycle, it is desirablethat the 1.,

constricted mouth of the inner conical passage 14 be smaller in sectionthan the constricted mouth of the outer conical passage 19, and such anarrangement is illustrated in the drawings and particularly in Fig. 2.With this arrangement, the reduction in pressure at the ring channel .3:

18 due to the flow of gases outwardly of the combustion chamber throughthe venturi tube 6, due to the high superatmospheric pressure of adetonation cycle, is sufficient to draw fuel from the ring channel andso to maintain fuel at the mouth of this channel at the start of the I;

ensuing suction cycle of operation. During a suction phase of operation,the inlet passage 4- is under vacuum which readily applies suctionsufiicient to draw fuel from the ring channel 18 under low velocity ofinward flow of gases through the venturi tube 6. No corresponding vacuumis available to draw fuel from the ring channel 18 during a detonationphase of operation, and for this reason a relatively hi her velocity offlow, producing an injector effect, is then desirable to draw fuel toand out of the ring channel 18.

I claim:

1. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube having a restricted throat intermediate its endsand connected between said fuel condensation chamber and said combustionchamber, a fuel feed pipe connected to deliver fuel to the restrictedthroat of said venturi tube, said condensation chamber having adischarge opening for fuel condensed therein, and means connecting saiddischarge opening with said fuel feed pipe whereby fuel condensed insaid condensation chamber may be passed back to said venturi tubethrough said fuel feed pipe.

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2. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube having a restricted throat intermediate its endsand connected between said fuel condensation chamber and said combustionchamber, a fuel storage container disposed below and connected toreceive fuel from said condensation chamber and a fuel feed pipeconnected between said fuel storage container and the restricted throatof said venturi tube.

3. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube having a restricted throat intermediate its endsand connected between said fuel condensation chamber and said combustionchamber, a fuel storage container disposed below and connected toreceive fuel from said condensation chamber, means for maintaining asupply of fuel in said fuel storage container, and a fuel feed pipeconnected between said fuel storage container and the restricted throatof said venturi tube.

4. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube comprising two conical passages convergingtoward each other to form a restricted throat with the outer ends ofsaid conical passages connected respectively to said fuel condensationchamber and said combustion chamber, the restricted end of said conicalpassage which is connected to said combustion chamber having a smallercross section than the restricted end of said conical passage which isconnected to said condensation chamber, and a fuel feed pipe connectedto deliver fuel to the restricted throat of said venturi tube at theperiphery of the constricted end of said conical passage which isconnected to said condensation chamber.

5. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube comprising two conical passages convergingtowards each other to form a restricted throat with the outer ends ofsaid conical passages connected respectively to said fuel condensationchamber and said combustion chamber, the restricted end of said conicalpassage which is connected to said combustion chamber having a smallercross section than the restricted end of said conical passage which isconnected to said condensation chamber, and means connected to deliverfuel from said condensation chamber to the restricted throat of saidventuri tube.

6. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube comprising two conical passages convergingtowards each other to form a restricted throat with the outer ends ofsaid conical passages connected respectively to said fuel condensationchamber and said combustion chamber, the restricted end of said conicalpassage which is connected to said combustion chamber having a smallercross section than the restricted end of said conical passage which isconnected to said condensation chamber, a fuel storage containerdisposed below and connected to receive fuel from said condensationchamber, and a fuel feed pipe connected between said fuel storagecontainer and the restricted throat of said venturi tube.

7. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube comprising two conical passages convergingtoward each other to form a restricted throat with the conical passagesrespectively connected at their outer ends to said combustion chamberand to said condensation chamber, and a fuel feed pipe connected todeliver fuel to the restricted throat of said venturi tube.

8. Apparatus of the type described comprising the com bination, with aresonant pulse jet combustion device in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant eX- haust pipedirectly connected with the combustion chamber and forming therewith anacoustic resonator, and an inlet check valve connected to the combustionchamber, of fuel supply apparatus comprising a fuel condensationchamber, a venturi tube comprising two conical passages convergingtoward each other to form a restricted throat with the conical passagesrespectively connected at their outer ends to said combustion chamberand to said condensation chamber, a baffie in said condensation chamberadjacent the connection of said venturi tube thereto for deflecting airand fuel to flow in a circular path in said condensation chamber, a fuelstorage chamber disposed below and connected to receive fuel from saidcondensation chamber, and a fuel feed pipe connected between said fuelstorage container and the restricted throat of said venturi tube.

9. Apparatus of the type described comprising the combination, with aresonant pulse jet combustion device, in which a combustible mixture offuel and air is periodically detonated at acoustic frequency and whichcomprises a combustion chamber, a valveless resonant exhaust pipedirectly connected with said combustion chamber and forming therewith anacoustic resonator, an inlet check valve and an inlet passage connectingsaid combustion chamber to said check valve, the combination of fuelsupply apparatus comprising a fuel condensation chamber, a venturi tubehaving a restricted throat intermediate its ends connected between saidfuel condensation chamber and said inlet passage, fuel conduit meansconnected to deliver fuel to the restricted throat of said venturi tube,and means for passing fuel condensed in said condensation chamber tosaid fuel conduit means.

10. Apparatus of the type described in claim 1 in which the inlet checkvalve is connected to the combustion chamber by an inlet passage and theventuri tube is connected between the fuel condensation chamber and saidinlet passage.

References Cited in the file of this patent UNITED STATES PATENTS2,427,845 Forsyth Sept. 23, 1947 FOREIGN PATENTS 270,782 SwitzerlandDec. 16, 1950

